Air reodorizing or deodorizing compositions in gel form are well-known in the art. Primarily they comprise an aqueous medium containing a volatile fragrance and a small amount of a gelling agent which renders the compositions in a gel-like or semi-solid form. These compositions are popular in that they are easy to handle, and on exposure to air, the aqueous medium gradually evaporates from the gel releasing the fragrance into the surrounding atmosphere. Aqueous gels of this type are claimed in U.S. Pat. Nos. 2,691,615 and 2,927,055 and in British Pat. No. 1,241,914.
One difficulty with most aqueous gels is that they are relatively short-lived. This is because of the rapid rate of release of water and fragrance from gels of this type, and because only a small part of the gel, i.e., from 1 to 10% of the aqueous phase, is available as a fragrance for acting as a reodorant. Also, because of the rapid rate of release of water, aqueous gels are necessarily large in size, thus limiting holder design and increasing shipping costs. Moreover, when subjected to low temperatures the aqueous gels might freeze which will result in excessive bleeding or gel decomposition upon thawing. In addition, aqueous gels are subject to microbial degradation.
As used in this application, the term "reodorant" means an air freshener whereby the odors in the surrounding atmosphere are masked or overcome by the fragrance emitted from the air freshener. As so defined this term is intended to include true deodorants which react with or destroy the odor which is to be overcome.
Various types of non-aqueous air fresheners have also been proposed. For example, U.S. Pat. No. 2,865,806 discloses an air odor control agent prepared by blending a menthadiene compound, and preferably an added antioxidant, with a selected solidifying agent at an elevated temperature and then cooling the blend. The solidifying agents are certain polyethylenes and ethyl celluloses. The menthadiene compounds are monocyclic terpenes containing nonconjugated double bonds, not more than one of which occurs outside the six carbon ring, i.e., d- or l-limonene or racemic mixtures (dipentene) may be used. An important feature of the disclosed non-aqueous air fresheners is said to be that bleeding or exudation of the dipentene to the surface of the molded product occurs which facilitates its removal from the mold.
While bleeding or exudation may be beneficial in aiding the release of the molded product, these properties are generally not desirable to the consumer since syneresis or bleeding during use can cause liquid droplets to come in contact with fabrics, furniture and other finishes within the home which may cause staining or other damage. Hence, from a consumer point of view, it is desirous to have a solid air reodorant which is storage stable, dry to the touch and yet which permits adequate release of a fragrance into the surrounding atmosphere over a sustained period of time.
An attempt to achieve these results is outlined in U.S. Pat. No. 3,688,985 wherein a pre-formed plastic object is soaked in a stable aqueous emulsion containing an essential oil and a surfactant to impregnate the resin with the essential oil thereafter drying the resin to yield a dry impregnated resin which gradually releases the essential oil into the surrounding atmosphere.
Also mentioned in U.S. Pat. No. 3,688,985 is British Pat. No. 599,237 wherein an essential oil is combined with a plasticized synthetic resin by dispersing the resin in a plasticizer, including the essential oil, which is gelled by heat to form the desired article. However, as reported, the essential oils when heated to the gelling temperatures break down, thereby causing a change in the chemical properties of the essential oil so that it can no longer be useful for the intended purpose.
Thus it can be seen that although considerable effort has been devoted to the development of stable, long-lived air reodorant formulations, considerable problems remain and there is continuing need for improved products. The present invention is directed to one such class of highly advantageous air reodorant compositions.